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23 votes
2 answers
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Dirichlet and the prime number theorem

I browsed Dirichlets Werke today and was kind of surprised by two remarks that he made on p. 354 (Über die Bestimmung ...) and p. 372 (Sur l'usage ...). In the second paper, he claims (my ...
Franz Lemmermeyer's user avatar
23 votes
3 answers
1k views

References for $K_{4k}(\mathbb{Z})$

Weibel's "Algebraic K-theory of rings of integers in local and global fields" says $K_{4k}(\mathbb{Z})$ are known to have odd order, with no prime factors less than $10^7$, but are conjectured to be ...
Myshkin's user avatar
  • 17.6k
23 votes
1 answer
4k views

Chapters 1--4 of the Artin-Tate notes on Class Field Theory

Emil Artin and John Tate held a seminar on class field theory at Princeton University in 1951--1952. Their notes were published in 1967 by Benjamin (New York), but the first four chapters covering (...
Chandan Singh Dalawat's user avatar
23 votes
1 answer
3k views

A list of proofs of the Hasse–Minkowski theorem

I am currently doing a project in which I intend to include the most insightful possible proof of the Hasse–Minkowski theorem (also known as the Hasse principle for quadratic forms, among other names) ...
22 votes
3 answers
2k views

Hecke equidistribution

For a prime $p\equiv 1\pmod{4}$, we can write $p=a^2+b^2=N(a+bi)$. Therefore $$ a+bi=p^{1/2}e^{i\varphi} $$ where $\varphi\in [0,2\pi]$. I know that Hecke proved that $\varphi$ is equidistributed. I ...
M.B's user avatar
  • 2,508
22 votes
2 answers
3k views

$p$-adic Langlands correspondence

Basic question: Is it correct that the $p$-adic Langlands correspondence is known for $GL_2$ only over $Q_p$ but not other $p$-adic fields? If so, I would like to request some light to be shed on this ...
SGP's user avatar
  • 3,867
22 votes
3 answers
7k views

A recommended roadmap to Fermat's Last Theorem

I was inspired to undertake math as a career after watching a documentary on the proof of Fermat's Last Theorem. As such it's been a small goal of mine to understand Wiles et al's proof. In a ...
Eugene's user avatar
  • 1,458
22 votes
1 answer
2k views

Reference request: The first cohomology of SL(2,Z) with coefficients in homogeneous polynomials

Let $H_k$ be the vector space of degree $k$ homogeneous polynomials in two variables.I'm looking for a reference for the fact that $H^1(SL(2,\mathbb Z);H_k)=M^0(k+2)\oplus\overline{M^0(k+2)}\oplus E_{...
Jim Conant's user avatar
  • 4,898
22 votes
1 answer
770 views

Writing $3p$ when $p \equiv 1 \pmod{3}$ as a sum of two rational cubes. Is this result new? And what about its converse?

I recently discovered a proof of the following. Let $p$ be a prime that's $1 \bmod {3}$. Suppose that $p$ is not represented by the principal quadratic form $(1,9,81)$ of discriminant $-243$ (The ...
paul Monsky's user avatar
  • 5,422
21 votes
2 answers
1k views

Most squares in the first half-interval

It is well known that if $p$ is an odd prime, exactly one half of the numbers $1, \dots, p-1$ are squares in $\mathbb{F}_p$. What is less obvious is that among these $(p-1)/2$ squares, at least one ...
Andrea Ferretti's user avatar
21 votes
5 answers
5k views

What arrangement of unit cubes minimizes surface area?

For each of these two questions, one can assume that the arrangements are polycubes (for which a definition can be found in the excerpt-image below). Question A. How does one arrange $n$ unit cubes ...
Benjamin Dickman's user avatar
21 votes
3 answers
3k views

Twin Prime Conjecture Reference

I'm looking for a reference which has the first statement of the twin prime conjecture. According to wikipedia, nova, and several other quasi-reputable resources it is Euclid who first stated it, but ...
Ben Weiss's user avatar
  • 1,588
21 votes
2 answers
2k views

Applications of number theory in dynamical systems

I am looking for references (or ways to find references) on significant and/or recent applications of techniques in number theory to problems in the areas of dynamical systems and nonlinear dynamics. ...
J W's user avatar
  • 760
21 votes
1 answer
771 views

Covering a set with geometric progressions

Consider the set $S_n=\{1,2,\cdots ,n\}$. What is the minimum number of distinct geometric progressions that cover $S_n$? Let us call this number $a_n$. I was wondering about this number after doing a ...
shadow10's user avatar
  • 1,090
20 votes
2 answers
4k views

information-theoretic derivation of the prime number theorem

Motivation: While going through a couple interesting papers on the Physics of the Riemann Hypothesis [1] and the Minimum Description Length Principle [2], a derivation(not a proof) of the Prime Number ...
Aidan Rocke's user avatar
  • 3,871
20 votes
4 answers
2k views

Does the set of happy numbers have a limiting density?

A positive integer $n$ is said to be happy if the sequence $$n, s(n), s(s(n)), s(s(s(n))), \ldots$$ eventually reaches 1, where $s(n)$ denotes the sum of the squared digits of $n$. For example, 7 is ...
Dave R's user avatar
  • 856
20 votes
2 answers
2k views

On a result attributed to W. Ljunggren and T. Nagell

I've read in a number of places that, building on previous work of T. Nagell, W. Ljunggren proved in 1 that the Diophantine equation $$\frac{x^{n}-1}{x-1} = y^{2}$$ doesn't admit solutions in ...
José Hdz. Stgo.'s user avatar
20 votes
1 answer
2k views

When complex conjugation lies in the center of a Galois group

Let $K \subseteq \mathbb{C}$ be a number field (I'm fixing an embedding), and assume $K/\mathbb{Q}$ is Galois with Galois group $G$. Let $\tau \in G$ denote complex conjugation. This question ...
Bobby Grizzard's user avatar
20 votes
6 answers
4k views

Erik Westzynthius's cool upper bound argument: update?

Version 2 of this writeup is available, and includes a newer and simple upper bound thanks to MathOverflow 88777 as well as indirect references to future writeups. Details of further work ...
Gerhard Paseman's user avatar
20 votes
1 answer
786 views

Representation theory of reductive groups in characteristic $p$ as a limit of the theories in characteristic $0$

This question is out of plain curiosity. The first sentence of Deligne's Les corps locaux de caractéristique $p$, limites de corps locaux de caractéristique $0$ (1984) reads (in rough translation) as ...
Chandan Singh Dalawat's user avatar
20 votes
1 answer
1k views

Curves over number fields with everywhere good reduction

My question is the following:$\newcommand{\Q}{\Bbb Q} \newcommand{\Z}{\Bbb Z}$ What is known about number fields $K$ fulfilling the condition $C_{g,K}$ "there is a smooth projective curve of ...
Watson's user avatar
  • 1,742
19 votes
1 answer
3k views

Mazur secret Bourbaki report "Analyse p-adique"

Does anyone happen to know if a scan of Mazur's report exists, and, if so, where to find it? It appears in the references for Katz's "Higher congruences" and "Eisenstein measure" papers.
19 votes
5 answers
2k views

Sum of the reciprocals of radicals

Recall that the radical of an integer $n$ is defined to be $\operatorname{rad}(n) = \prod_{p \mid n } p$. For a paper, I need the result that $$\sum_{n \leq x} \frac{1}{\operatorname{rad}(n)} \ll_\...
Daniel Loughran's user avatar
19 votes
2 answers
2k views

Who first proved the generalization of Bertrand's postulate to (2n,3n) and (3n,4n)?

In Wikipedia's page for Bertrand's postulate, it is said that its (2n,3n) version was proved by El Bachraoui in 2006. Seems likely that it was first proved way before than that! Can anyone point to ...
Jose Brox's user avatar
  • 2,992
19 votes
1 answer
1k views

Deligne's letter to Bhargava from March 2004

I am quite interested in moduli spaces for Rings and Ideals, a letter from Deligne to Bhargava is cited in Melanie Wood's thesis Moduli spaces for Rings and Ideals (pdf), studying the minimal free ...
loos's user avatar
  • 461
19 votes
3 answers
1k views

Points of elliptic curves over cyclotomic extensions

Let $E$ be an elliptic curve over $\mathbb Q$. Let's look at the group of points of this elliptic curve over $\mathbb Q(1^{1/\infty})$ which we get after adding all roots of unity to $\mathbb Q$. It ...
cll's user avatar
  • 2,305
19 votes
3 answers
2k views

Cyclotomic polynomials: $\Phi_n(p)$ is like $p^{\phi(n)}$ for big enough $p$, right?

Apologies in advance if this turns out to be simple. So far I haven't found a proof or a reference. Although I like $p$ to be a prime, I can ask the following for positive integers $n$ and $p$, ...
Gerhard Paseman's user avatar
19 votes
1 answer
2k views

Has anything ever been done with the set $\{1,2,3,4,\ldots\}$ equipped with the operation $a \oplus b = a+b-1$ and the usual notion of multiplication?

Definition. $$\mathbb{J} = \{1,2,3,\ldots\}.$$ We can refer to the elements of $\mathbb{J}$ as "joiners." The product of joiners is inherited from $\mathbb{Z}$. The sum of joiners will be ...
goblin GONE's user avatar
  • 3,793
19 votes
1 answer
2k views

"The Galois group of $\pi$ is $\mathbb{Z}$."

Last year, in a talk of Michel Waldschmidt's, I remember hearing a statement along the lines of the title of this question, that is, "The Galois group of $\pi$ is $\mathbb{Z}$.". In what sense/...
Joshua Seaton's user avatar
19 votes
1 answer
1k views

Definitions of $\pi_1 \times \pi_2, \pi_1 \boxplus \pi_2, \pi_1 \boxtimes \pi_2$

Let $\pi_i$ be a smooth, admissible (possibly irreducible) representation of $\operatorname{GL}_{n_i}(k)$ for $k$ a $p$-adic field. I have seen the following representations defined in terms of $\...
D_S's user avatar
  • 6,180
19 votes
1 answer
2k views

Legendre and sums of three squares

The Three-Squares-Theorem was proved by Gauss in his Disquisitiones, and this proof was studied carefully by various number theorists. Three years before Gauss, Legendre claimed to have given a proof ...
Franz Lemmermeyer's user avatar
19 votes
1 answer
1k views

Ehresmann's theorem over the $p$-adics

I am looking for a version of Ehresmann's theorem for analytic manifolds over the $p$-adic numbers $\mathbb{Q}_p$ or, more generally, local fields. I follow the conventions from Serre's book "Lie ...
Daniel Loughran's user avatar
19 votes
0 answers
523 views

univariate integer version of Hilbert's 17th problem

Let $f(x)$ be a polynomial of degree $d$ with integer coefficients such that $f(x)\geqslant 0$ for all real $x$. Is it necessarily true that there exists an integer $N(d)$ such that $N(d)\cdot f$ is a ...
Fedor Petrov's user avatar
18 votes
2 answers
3k views

Only odd primes?

For $k \ge 2$, let $$u = \{\lfloor{(k - \sqrt{k})n}\rfloor : n \ge 1\}$$ $$v = \{\lfloor{(k + \sqrt{k})n}\rfloor : n \ge 1\}.$$ My computer suggests that $u$ and $v$ are disjoint if and only if $k$ is ...
Clark Kimberling's user avatar
18 votes
6 answers
2k views

Explicit formula for the trace of an unramified principal series representation of $GL(n,K)$, $K$ $p$-adic.

Let $K$ be a non-arch local field (I'm only interested in the char 0 case), let $\mathbb{G}$ be a connected reductive group over $K$ and let $G=\mathbb{G}(K)$. If $V$ is a smooth irreducible complex ...
Kevin Buzzard's user avatar
18 votes
5 answers
3k views

An elementary, short proof that the group of units of the ring of integers of a number field is finitely generated

Dirichlet's unit theorem states that (i) the group of units, $\mathscr{U}_K$, of the ring of integers of a number field $K$ is finitely generated, and (ii) the rank of $\mathscr{U}_K$ is equal to $r_1 ...
Salvo Tringali's user avatar
18 votes
3 answers
6k views

The multiplicative order of 2 modulo primes

Artin's Conjecture says that any positive integer, which is not a square, is a primitive root modulo infinitely many primes. Christopher Hooley gave in Hooley, Christopher (1967). "On Artin's ...
Andreas Thom's user avatar
  • 25.5k
18 votes
2 answers
3k views

References for Artin motives

I find the following description of Artin motives in Wikipedia. Since these seem to be quite related to number theory, I am interested to learn more in that context. I request the experts available in ...
Anweshi's user avatar
  • 7,442
18 votes
1 answer
1k views

Distinct integer roots for a degree 7+ polynomial and its derivative

Question: Is there a polynomial $f \in \mathbb{Z}[x]$ with $\deg(f) \geq 7$ such that all roots of $f$ are distinct integers; and all roots of $f'$ are distinct integers? Background: I asked a ...
Benjamin Dickman's user avatar
18 votes
3 answers
745 views

Number of primitive $n$th roots with positive versus negative real parts

Does anyone know a reference to the following results, which I can prove, but I suspect may be known. Let $R(n)$ denote the number of primitive $n$th roots of unity with positive real part, and $L(n)$ ...
Glasby's user avatar
  • 1,991
18 votes
1 answer
631 views

Best texts on Lie groups for number theorists

What are the most comprehensive textbooks on the structure of Lie groups and their infinite-dimensional representations if one is interested in their applications to number theory (so covering ...
user163784's user avatar
18 votes
1 answer
562 views

Is special value of Epstein zeta function in 3 variables a period?

Kontsevich-Zagier's article "Periods" contains the following question Is $\displaystyle \sum_{x,y,z \in \mathbb{Z}}' \frac{1}{(x^2+y^2+z^2)^2}$ an extended period? ($\sum'$ means we do not sum ...
Pig's user avatar
  • 809
18 votes
0 answers
718 views

Erdos-Kac for squarefree numbers

In its usual form, the Erdos-Kac Theorem states that if $f(n) : \mathbb{N} \rightarrow \mathbb{R}$ is a strongly additive function with $|f(p)| \le 1$ for all primes $p$, then $$\frac{|\{n \le x : \...
Zev's user avatar
  • 211
17 votes
13 answers
6k views

Probability in number theory

I am hearing that there are some great applications of probability theory (or more general measure theory) to number theory. Could anyone recommend some good book(s) on that (or other types of ...
17 votes
5 answers
4k views

Fermat numbers and the infinitude of primes

Wonder whether any of you guys know why it is that the proof of the infinitude of primes that is based on the coprimality of any pair of (distinct) Fermat numbers is commonly attributed to Pólya. In ...
José Hdz. Stgo.'s user avatar
17 votes
2 answers
3k views

Consequences of the Birch and Swinnerton-Dyer Conjecture?

Before asking my short question I had made some research. Unfortunately I did not find a good reference with some examples. My question is the following What are the consequences of the Birch and ...
17 votes
1 answer
3k views

Is $x^{n}-x-1$ irreducible?

Is it true that for every $n \in \mathbb{N}$, $x^{n}-x-1$ is irreducible in $\mathbb{Z}[x]$? The standard irreducibility criteria seem to fail.
Pablo's user avatar
  • 11.3k
17 votes
1 answer
2k views

Is there an analog of the Birch/Swinnerton-Dyer conjecture for abelian varieties in higher dimensions?

I am wondering if there is a multi-dimensional analog of the Birch/Swinnerton-Dyer (BSD) conjecture. The recent famous result inching toward resolution of that conjecture is: Bhargava, Manjul, and ...
Joseph O'Rourke's user avatar
17 votes
2 answers
1k views

The GCD-matrix: generalizing a result of Smith?

Let $M$ be the $n\times n$ matrix, known as the GCD matrix, of entries $M_{ij}=\gcd(i,j)$. In the paper H J S Smith, On the value of a certain arithmetical determinant, Proc. London Math. Soc. 7:208-...
T. Amdeberhan's user avatar
17 votes
2 answers
2k views

Why does Tate's conjecture imply semisimplicity of crystalline Frobenius?

I'm trying to find a reference for the following fact: If Tate's conjecture is true for all smooth projective varieties over $\mathbb{F}_p$, then the Frobenius endomorphism on the crystalline ...
David Loeffler's user avatar

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